Surgical technique and instrumentation for minimal incision hip arthroplasty surgery

ABSTRACT

Improved instruments for modifying a shape of a proximal femur of a patient for installation of a stem of a femoral component of a prosthetic hip during hip replacement surgery, comprising a handle including an elongated shaft extending downward approximately in a z-direction, a first offset extending from a bottom of the elongated shaft approximately in a y-direction, a second offset extending from the second offset approximately in an x-direction, and a shaping member elongated downward from the second offset approximately in the z-direction. Provided is an improved femoral broach and an improved osteotome. Also provided is a method of improving a patient&#39;s positioning during hip replacement surgery by using a variable configuration mattress for positioning the patient.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of Ser. No. 10/991,641, filedNov. 18, 2004, entitled “SURGICAL TECHNIQUE AND INSTRUMENTATION FORMINIMAL INCISION HIP ARTHROPLASTY SURGERY,” which claims the benefit ofU.S. Provisional Patent Application No. 60/520,970 filed Nov. 18, 2003,the entire contents of all of which are herein incorporated byreference.

FIELD OF THE INVENTION

The present invention relates to methods and instruments used forminimal incision surgery, and, more particularly, to method andinstruments used to prepare a patient's femur prior to the implantationof a hip prosthesis' femoral component during hip replacement.

BACKGROUND

Joint implants, also referred to as joint prostheses, joint prostheticimplants, joint replacements, or prosthetic joints, are long-termsurgically implantable devices that are used to partially or totallyreplace diseased or damaged joints, such as a hip, a knee, a shoulder,an ankle, or an elbow, within the musculoskeletal system of a human oran animal. Since their first introduction into clinical practice in the1960s, joint implants have improved the quality of life of manypatients. Both artificial hip joints and artificial shoulder joints aregenerally ball and socket joints, designed to match as closely aspossible the function of the natural joint. Generally, the artificialsocket is implanted in one bone, and the artificial ball articulates inthe socket. A stem structure attached to the ball is implanted inanother of the patient's bones, securing the ball in position.

The ball and socket joint of the human hip unites the femur to thepelvis, wherein the bali-shaped head of the femur is positioned within asocket-shaped acetabulum of the pelvis. The head of the femur or ballfits into the acetabulum, forming a joint which allows the leg to moveforward, backward, and sideways in a wide range. The acetabulum is linedwith cartilage, which cushions the bones and allows the joint to rotatesmoothly and with minimal friction. An envelope of tough ligamentsconnects the pelvis and femur, covering the joint and stabilizing it.Cartilage also makes the joint strong enough to support the weight ofthe upper body and resilient enough to absorb the impact of exercise andactivity. A healthy hip allows the leg to move freely within its rangeof motion while supporting the upper body and absorbing the impact thataccompanies certain activities.

Various degenerative diseases and injuries may necessitate replacementof all or a portion of a hip using synthetic materials. Prostheticcomponents are generally made from metals, ceramics, or plastics, orcombinations of them.

Total hip arthroplasty and hemi-arthroplasty are two procedures wellknown within the medical profession for replacing all or part of apatient's hip. These procedures have enabled hundreds of thousands ofpeople to live fuller, more active lives. A total hip arthroplastyreplaces both the femoral component and the acetabular surface of thejoint, and so both a femoral prosthesis and an acetabular prosthesis arerequired. A hemi-arthroplasty may replace either the femoral componentor the acetabular surface of the joint. The purpose of hip replacementsurgery is to remove the damaged and worn parts of the hip and replacethem with artificial parts, called prostheses, with the purpose of atleast partially restoring the hip's function, including but not limitedto, restoring the stability, strength, range of motion, and flexibilityof the joint.

In total hip replacement surgery, commonly referred to as total hiparthroplasty, a patient's natural hip is replaced by two maincomponents: an acetabular cup component that replaces the acetabularsocket, and the femoral component, or the stem-and-ball component, thatreplaces the femoral head.

A conventional acetabular cup component may include a cup, a cup and aliner, or in some cases only a liner, all of which may be formed invarious shapes and sizes. Generally, a metal cup and a polymeric linerare used. However, the liner may be made of a variety of materials,including polyethylene, ultra high molecular weight polyethylene, andceramic materials. The cup is usually of generally hemispherical shapeand features an outer, convex surface and an inner, concave surface thatis adapted to receive a cup liner. The liner fits inside the cup and hasa convex and concave surface. The cup liner is the bearing element inthe acetabular component assembly. The convex surface of the linercorresponds to the inner concave surface of the cup or acetabulum, andthe liner concave surface receives the head of a femoral component. Anacetabular cup may include a highly polished inner surface to decreasewear.

The femoral or stem-and-ball component of the hip prosthesis generallyincludes a spherical or near-spherical head attached to an elongatestem, with a neck connecting the head and stem. In use, the elongatestem is located in the intramedullary canal of the femur, and thespherical or near-spherical head articulates relative to the acetabularcomponent. Femoral prostheses used in total hip arthroplasty proceduresmay or may not differ from an endoprosthesis used in ahemi-arthroplasty. The femoral head of each type prosthesis is generallya standard size and shape. Various cups, liners, shells, stems and othercomponents may be provided in each type arthroplasty to form modularprostheses to restore function of the hip joint.

During a total hip replacement, the surgeon will take a number ofmeasurements to ensure proper prosthesis selection, limb length, and hiprotation. After making the incision, the surgeon works between the largehip muscles to gain access to the joint. The femur is pushed out of thesocket, exposing the joint cavity. The deteriorated femoral head isremoved.

In order to install the acetabular cup, the surgeon prepares the bone byreaming the acetabular socket to create a surface for accepting a cup.The cup may be held in place by bone cement or an interference or pressfit, or it may have a porous outer surface suitable for bony ingrowth.The new acetabular shell is implanted securely within the preparedhemispherical socket. The plastic inner portion of the implant is placedwithin the metal shell and fixed into place.

Next, the femur is prepared to receive the stem. The proximal end of thefemur is at least partially resected to expose the central portion ofthe bone. Generally, at least part of the greater femoral trochanter isresected to gain access to the central portion of the femur,specifically, the medullary canal. In the central portion, a cavity iscreated that matches the shape of the implant stem, utilizing theexisting medullary canal. The top end of the femur is planed andsmoothed so that the stem can be inserted flush with the bone surface.If the ball is a separate piece, the proper size is selected andattached. Finally, the ball is seated within the cup so that the jointis properly aligned, and the incision is closed.

During shoulder replacement, the ball and socket joint of the humanshoulder is replaced with a prosthetic joint using a procedure similarto that described above. During a shoulder replacement operation, atleast a portion of the proximal section of the humeral shaft is replacedby a metal prosthesis. This prosthesis generally consists of two parts:a stem that is mounted into the medullary canal of the humerus, and ahead component connected in some manner to the stem. The head componentreplaces the bearing surface of the humerus and articulates within theglenoid cavity of the scapula to allow movement of the shoulder.

An arthritic humeral head (ball of the joint) may be removed andreplaced with a humeral prosthesis. If the glenoid socket is unaffected,a hemiarthroplasty may be performed (which means that only the ball isreplaced). The humeral component is made of metal and is usually pressfit, but sometimes cemented, into the shaft of the bone of the humerus.

If the glenoid is affected, but conditions do not favor the insertion ofa glenoid component, a non-prosthetic glenoid arthroplasty may beperformed along with a humeral hemiarthroplasty. In this procedure, thehumeral prosthesis is installed, and the patient's glenoid shape andorientation are corrected to articulate the humeral prosthesis, forexample, by reshaping the socket by reaming. The prosthetic ball of thehumeral component then articulates with the reshaped bony socket of theglenoid. In a total shoulder joint replacement, or total humeralarthroplasty, the glenoid bone is shaped by reaming and oriented, andthen covered with a prosthetic glenoid component that is commonlystabilized by bone cement.

During joint replacement surgery, such as the procedures describedabove, a rather large incision is typically required to allow thesurgeon adequate access to the joint. The large incision is needed toproperly use the instruments needed to prepare the bones forinstallation of the prosthetic joint components and to install theprosthesis itself. For example, during total hip replacement surgery,some conventional surgical techniques generally require an approximately25 to 35 cm incision in the lateral (side) or posterior (back) aspect ofthe patient for installing, respectively, the acetabular component andthe femoral component of the prosthetic hip. Other conventional surgicaltechniques include two smaller incisions: a first, anterior incision toinstall the acetabular member; and the second, posterior incision toinstall the femoral component. In this technique, both the first and thesecond incisions are approximately 3 cm to approximately 5 cm in length.The two-incision technique is considered advantageous over the oneincision technique because it minimizes the trauma to the patient andresults in quicker and better patient rehabilitation than the techniqueinvolving a longer incision. Currently available data suggests that thelonger incision, either posterior or lateral, increases patientmorbidity. Thus, for joint replacement surgery, particularly for hipreplacement surgery, it is desirable to reduce the size and the numberof the incisions without jeopardizing surgical access to the joint.

Patient positioning during hip arthroplasty is important for surgicalaccess, proper preparation of the joint, and installation of theprosthetic components. Both initial positioning of the patient for thesurgery and maintenance of the patient's position throughout the surgeryare essential. Various approaches to improving patient positioningexist. For example, some of the conventional hip arthroplasty techniquesuse supine (on the back) positioning of the patient, with an operatingor surgical table including a dropping part on one side of the lowerend. This allows the lowering of the patient's operative leg forincreased access to the proximal femur.

During recent years, an effort has been made to reduce the size of theincision needed to implant joint prostheses through so-called “minimallyinvasive” surgery (“MIS”). The term “minimally invasive surgery”generally refers to the surgical techniques that minimize the size ofthe surgical incision and trauma to tissues, and are generally lessintrusive than conventional surgery, thereby shortening both surgicaltime and recovery time. Minimally invasive arthroplasty techniques areadvantageous over conventional arthroplasty techniques by providing, forexample, a smaller incision, less soft-tissue exposure, improvedligament balancing, and minimal trauma to the muscle and ligamentmechanisms. To achieve the above goals of MIS, it is necessary to modifytraditional implants, instruments, and surgical techniques to decreasethe length and number of the surgical cuts, as well as to decrease theexposure of and trauma to the internal joint structures. The benefits ofMIS surgery can be significant, at least partially because smaller andfewer incisions and the less intrusive nature of the procedure shortenboth surgical time and recovery time. Thus, it is advantageous to modifytraditional implants, instruments, and methods to make them particularlysuitable for use in minimally invasive surgical procedures.

Another recent development in joint replacement is computer-assisted orcomputer-aided surgical (CAS) systems that use various imaging andtracking devices and combine the image information with computeralgorithms to track the position of the patient's leg, the implant, andthe surgical instruments and to make highly individualizedrecommendations on the most optimal surgical cuts and prostheticcomponent selection and positioning. Several providers have developedand are marketing imaging systems based on CT scans and/or MRI data oron digitized points on the anatomy. Other systems align preoperative CTscans, MRIs, or other images with intraoperative patient positions. Apreoperative planning system allows the surgeon to select referencepoints and to determine the final implant position. Intraoperatively,the system calibrates the patient position to that preoperative plan,such as by using a “point cloud” technique, and can use a robot toperform surgical procedures. Other systems use position and/ororientation tracking sensors, such as infrared sensors actingstereoscopically or otherwise, to track positions of body parts,surgery-related items such as implements, instrumentation, trialprosthetics, prosthetic components, and virtual constructs or referencessuch as rotational axes that have been calculated and stored based ondesignation of bone landmarks. Processing capability such as any desiredform of computer functionality, whether standalone, networked, orotherwise, takes into account the position and orientation informationas to various items in the position sensing field (which may correspondgenerally or specifically to all, portions, or more than all of thesurgical field) based on sensed position and orientation of theirassociated fiducials or based on stored position and/or orientationinformation. The processing functionality correlates this position andorientation information for each object with stored informationregarding the items, such as a computerized fluoroscopic imaged file ofa bone, a wire frame data file for rendering a representation of aninstrumentation component, a trial prosthesis or actual prosthesis, or acomputer generated file relating to a rotational axis or other virtualconstruct or reference. The processing functionality then displaysposition and orientation of these objects on a screen or monitor orotherwise. The surgeon may navigate tools, instrumentation, trialprostheses, actual prostheses and other items relative to bones andother body parts in order to perform joint replacement more accurately,efficiently, and with better alignment and stability. Instruments andsurgical techniques that can be used in computer-assisted surgery arehighly desirable.

It is highly desirable to adapt the surgical instruments used inpreparation of the femoral bone during hip replacement to minimallyinvasive surgery, computer assisted surgery, or both. The instrumentsused in femoral preparation include, but are not limited to, osteotomesor chisels used for resecting at least a portion of the femoral head toexpose the central portion of the femur, and broaches, reamers, andrasps, used to clean and enlarge the hollow center of the bone, creatinga cavity that matches the shape of the femoral component's stem.

During hip replacement surgery, the surgeon opens a femoralintramedullary canal by removing a portion of the trochanteric fossawith an osteotome or a chisel, an instrument for surgical division orsectioning of bone. The surgeon then uses one or a series of increasingsize cavity preparation devices, such as reamers or broaches, to preparea cavity for installation of a femoral stem. By using a series ofgradually increasing in size devices, the surgeon expands theintra-femoral cavity until the desired size and shape is created.Sometimes, the portion of the final broach inserted into the femoralcavity serves as a trial femoral stem.

For the success of hip replacement, it is generally desired to selectand install the femoral stem of the largest size suitable for aparticular patient. Electing the largest appropriate femoral stem helpsto stabilize the femoral component in the femur, improves alignment, andreduces the potential of the femoral component's loosening and failure.There is a need for instruments and method for preparation of a femoralcavity that permit installation of an appropriately sized stem of thefemoral component in order to improve alignment and stabilization of thefemoral component in the patient with minimum interference the tissue ofthe patient

In minimally invasive surgery, the need to insert and operate thefemoral preparation instruments through smaller incisions may conflictwith the proper instrument alignment needed to create the cavity of thelargest possible size. For proper access and alignment, long incisionsand other invasive procedures are often required. The single-incisionlateral or posterior approach hip-arthroplasty procedure may simplifyaccess to the femur, but it requires muscle dissection. The two-incisionprocedures, on the other hand, make approach to the femur difficult.When the anterior approach to the femur is used, muscle dissection isnot necessary, but properly positioning the femur to allow access alongthe long axis often requires releasing the posterior hip capsule. Theposterior capsule comprises a blood vessel, and surgically releasing thecapsule greatly releases the risk of bleeding. The anterior approachused with some traditional instruments, such as straight femoralreamers, results in extensive trauma to the patient's tissues.Therefore, there is an unrealized need for instruments and techniquesfor preparation of a femoral cavity that reduce the incision size andtrauma to tissues without jeopardizing preparation of the cavity of thelargest appropriate size, which provide for proper sizing and alignmentof the femoral component's stem, and which will improve restoration ofhip function and reduce the risk of the prosthesis loosening andfailing.

In summary, there is a current unrealized need for improved devices,systems and procedures adapted for use in minimally invasive surgery(MIS). There is a particular unrealized need for improved devices forpreparation of a patient's femur for installing a femoral component of ahip prosthesis. Improved devices are desired that are adapted forintroduction and operation through a smaller surgical incision thanconventionally available devices. Also needed are improved devices,systems, and procedures that would minimize the damage to the flesh,muscle, and other soft tissues during insertion, operation, andwithdrawal. At the same time, there is a need for improved devices,systems, and procedures that would improve sizing and aligning of thefemoral components and reduce the risk of their loosening. Also desiredare improved devices, systems, and procedures suitable forcomputer-assisted surgery.

In general, devices and systems are needed that are easy to use andmanufacture, minimize tissue damage, simplify surgical procedures, areversatile, allow for faster healing with fewer complications, requireless post-surgical immobilization, and are less costly to produce andoperate.

SUMMARY

According to various aspects and embodiments of the present invention,there are provided devices, systems, instruments and methods forpreparation of a femur for installing a femoral component of a hipprosthesis. More specifically, certain aspects and embodiments of thepresent invention provide systems for modifying the shape, or shaping,of a proximal femur of a patient for installation of a stem of thefemoral component during total or partial hip replacement surgery.Modifying the shape of a proximal femur includes, but is not limited to,resection of bone or other tissues, preparation of a femoral cavity forreceiving the stem of the femoral component, or both.

Improved instruments for modifying the shape of a proximal femur of apatient for installation of a stem of a femoral component of aprosthetic hip during hip replacement surgery, comprise a handleincluding an elongated shaft extending downward approximately in az-direction, a first offset extending from a bottom of the elongatedshaft approximately in a y-direction, a second offset extending from thesecond offset approximately in an x-direction, and a shaping memberelongated downward from the second offset approximately in thez-direction. When the patient is in a supine position during surgery,during and upon installation of the instruments, the offsets locate thehandle in a general medial-lateral direction away from the shapingmember and vertically out of the surgical wound. The offsets allowinstallation of the instrument into the hip joint through an incisionthat is smaller than required for installation of the conventionalinstruments, and minimizes or eliminates the need to resect theposterior capsule. The improved systems also eliminate the need todeliver the femur out of the surgical wound for preparation.

The devices, systems, instruments and methods according to aspects andembodiments of the present invention are especially well suited for usein minimally invasive hip arthroplasty. The devices can be used inconjunction with image guided navigational systems, computer-assistedsystems, or other systems for precision guiding. The devices, systemsand instruments can further comprise fiducials for permitting thetracking of the position and orientation of the instruments or devicesby the position sensors. The devices, systems, instruments and methodsaccording to certain aspects and embodiments of the present inventionare not limited to use in minimally invasive surgery orcomputer-assisted surgery but can also be adapted for use inconventional hip arthroplasty or other surgical procedures.

The disclosed embodiments of the present invention provide femoralpreparation devices, instruments, and systems comprising such devicesand instruments, that allow installation and use through a minimallyinvasive surgical incision. According to aspects and embodiments of thepresent invention, the instruments for preparation of the femur include,but are not limited to, osteotomes, chisels, broaches, reamers or rasps.The instruments typically comprise shaping members, which may furthercomprise cutting elements such as teeth or sharp edges, or otherelements for shaping of bone tissue and/or other tissues. The shapingmember is typically at least partially inserted into the hip jointduring surgery. In an instrument for preparation of a femoral cavity,such as a broach, the shaping member is typically at least partiallyinserted into the femur, more specifically, into the intramedullarycanal of the femur.

The devices and instruments according to the aspects and embodiments ofthe present invention can include, be connected to, or used inconjunction with heads, handles, drills, mallets, or other implementsfor directing and manipulating the devices. The devices and instrumentscan comprise cannulated or hollow structures. The devices andinstruments can also include one or more shafts connecting variouselements. The devices, instruments, or systems can be one-piece ormulti-piece, or modular. In modular devices, instruments and systems,elements of the devices can be connected and used in variouscombinations, thereby increasing the system's versatility. Additionally,the instruments, devices, and systems of the present invention canincorporate elements of variable shape, such as flexible elements.

During use, the femoral preparation devices are rotated or moved eitherby hand or operated with a power tool, so that the cutting implementsshape bone, cartilage, marrow, and other tissues. In some cases, thedevices are adapted to remove the tissue in small pieces. The resectedtissue may pass through or be contained within the central cavity of thedevice, may pass outside the device, or may be removed by appropriateimplements.

The uses of the devices and instruments according to embodiments of thepresent invention are not limited to hip arthroplasty. They may also beused in connection with various other situations where resecting bone,creating a central cavity in a bone, or both, is desirable.Particularly, the devices and instruments according to aspects andembodiments of the present invention can be adapted to a range of jointarthroplasties.

In one embodiment, the osteotome systems are provided for resecting atleast a portion of the patient's femoral head, particularly at least aportion of the greater trochanter prominence, when preparing the femurfor installation of a hip prosthesis' femoral component. In a profferedembodiment a box osteotome comprising an approximately box-shapedcutting section with an open distal end is used to remove anapproximately box-shaped portion of a patient's femoral head and to opena femoral canal. In another embodiment broach systems are provided forpreparation of a requisite femoral cavity in a patient's femur adaptedfor installation of the stem of the femoral component of a hipprosthesis.

In one embodiment, the systems and methods of the present inventionallow the surgeon to advantageously realize the anterior approach to thefemoral head during hip replacement surgery without releasing theposterior hip capsule, thereby decreasing trauma to the patient and riskof bleeding. By allowing the surgeon to advantageously use an improvedanterior approach, rather than a posterior or a lateral approach thatrequire extensive muscle dissection, the systems and methods of thepresent invention improve the hip arthroplasty patient's recovery. Thesystems and methods of the present invention can be advantageously usedwith a variety of prosthetic hip systems, including, but not limited tothe conventional systems, such as those employing a Mueller femoral stemthat traditionally requires a posterior/lateral approach forinstallation.

The instruments and systems according to aspects and embodiments of thepresent invention can be made of a variety of materials suitable forsurgical instruments, including but not limited to metals, plastics,polymers, glass, ceramics, composite materials, or any combination orvariation of those. Methods of using the improved instruments forpreparation of a hip joint for installation of a prosthetic hip,particularly for preparation of a femur for installation of theprosthetic hip's femoral component, are also provided.

According to some aspects, the embodiments of the present inventionprovide hip arthroplasty systems and methods that improve patientpositioning during hip replacement surgery, thereby simplifying accessto the femur. In one embodiment, improved patient positioning isachieved by employing a mattress of variable configuration that allowspositioning of a patient's leg for better access during hiparthroplasty.

In certain aspects and embodiments, the instruments, systems, andmethods of the present invention minimize the size, the number, or bothof the surgical incisions required for installation of a hip prosthesisand trauma to patient's tissues resulting from the surgery. In oneaspect, the embodiments of the present invention are directed atminimizing the surgical incision and tissue trauma resulting frominstallation of a femoral component of a prosthetic hip joint.

The systems and methods according to some aspects and embodiments of thepresent invention allow installation of a hip prosthesis using onesurgical incision, preferably an anterior incision. One advantage ofusing a single, preferably anterior, incision, is that it avoids thedissection of muscles during the surgical approach, resulting in lesstrauma to the patient, quicker recovery, and quicker return to normaldaily activity

In yet one more aspect, the embodiments of the present invention providea method for improving patient positioning during hip arthroplasty. Theimproved method allows better access to the hip joint, particularly tothe femur, and permits quick and simple modification of the conventionalsurgical systems used in hip arthroplasty to improve patientpositioning.

It is to be understood that principles and concepts of the aspects andembodiments of the present invention are not limited to structures,methods, and applications provided herein but can be applied to anysuitable surgical application or device. Modifications and combinationsof the foregoing aspects of the present invention are envisioned andfall within its scope.

The foregoing discloses preferred embodiments of the present invention,and numerous modifications or alterations may be made without departingfrom the spirit and the scope of the invention.

The drawings illustrating preferred embodiments of the presentinvention, are schematic representation. The actual systems, devices andmethods according to the preferred embodiments of the present inventionmay depart from the foregoing schematics.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic isometric view of an improved femoral broach.

FIG. 2 is a schematic front view of an improved femoral broach.

FIG. 3 is a schematic side view of an improved femoral broach.

FIG. 4 is a schematic top view of an improved femoral broach.

FIG. 5 shows a schematic model of an improved femoral broach.

FIG. 6 shows a schematic model of an improved femoral broach.

FIG. 7 is a schematic isometric view of an improved femoral osteotome.

FIG. 8 is a schematic front view of an improved femoral osteotome.

FIG. 9 is a schematic side view of an improved femoral osteotome.

FIG. 10 is a schematic top view of an improved femoral osteotome.

FIG. 11 is an isometric view of a cutting element of a box osteotome.

FIG. 12 is a schematic representation of a method of improved patientpositioning during hip arthroplasty.

PREFERRED EMBODIMENTS Femoral Broach

FIGS. 1-6 show an improved femoral broach (100). For ease of descriptionthe devices disclosed herein will be described with respect to Cartesiancoordinates, in which the x- and y-axes lie in a horizontal plane, andthe z-axis extends vertically. However, it will be appreciated that thismethod of description is for convenience only and is not intended tolimit the invention to any particular orientation. Likewise, unlessotherwise stated, terms used herein such as “top,” “bottom,” “upper,”“lower,” “left,” “right,” “front,” “back,” “proximal,” “distal,”“medial,” “lateral,” “inferior,” “superior,” “anterior,” “posterior” andthe like are used only for convenience of description and are notintended to limit the invention to any particular orientation.

The improved femoral broach (100) comprises a handle (102) an elongatedshaft (102A) extending downward from the knob approximately in thez-direction. At the bottom of the handle shaft (102A), a first offset(104) extends transversely approximately in the y-direction. At theother end of the first offset (104), a second offset (105) extendstransversely approximately in the x-direction. At the other end of thesecond offset (105), a shaping member (101) is elongated downwardapproximately in the z-direction and is adapted for insertion into thefemoral cavity.

The double offset of the handle member (102) with respect to the shapingmember (101) simplifies the approach to the femur, and permits insertingand operating the broach through a minimally invasive surgical incision,reducing the need for the posterior capsule resection during anteriorapproach to the femur. In a preferred embodiment, this configurationallows the surgeon to advantageously utilize the anterior approach overmore invasive lateral or posterior approaches. The double offset of thehandle (102) with respect to the shaping member (101) permits aligningthe shaping member (101) with the long axis of the femur, at the sametime directing the handle up and out of the surgical site, renderingvertical approach to the femur unnecessary.

During surgery, the first offset (104) elevates the handle (102) out ofthe wound during and upon insertion of the broach. When the patient isin a supine position, during and upon insertion of the broach, thehandle (102) of the broach is elevated in a generally verticaldirection. The second offset (104) minimizes the trauma to the bone andto the soft tissues. When the patient is in a supine position, thesecond offset (104) locates the handle away from the shaping member inthe general medial/lateral direction

The broaches according to the embodiment shown in FIGS. 1-6 can beadvantageously inserted through a minimally invasive surgical incisionand are particularly advantageous for anterior access to the femur thatis preferred to the lateral or posterior access that requiressignificant muscle dissection, increasing the surgical time and the timerequired for the patient to return to normal daily activities. In apreferred embodiment, the incision for inserting the improved femoralbroach is between approximately 4 to approximately 16 cm. The broachesaccording to the embodiment shown in FIGS. 1-6 can be advantageouslyutilized with a variety of hip prostheses, such as, but not limited to,those employing the Mueller femoral stem. In a preferred embodiment, thebroaches according to the embodiment shown in FIGS. 1-6 allow thesurgeon to utilize a less invasive anterior approach without posteriorcapsule release in order to install a femoral member of the hipprosthesis.

When preparing the femoral cavity for installation of the prosthetic hipfemoral component, the surgeon inserts into and may rotate along themedial arc of the femoral intramedullary canal or cavity a series of thebroaches of increasing size, thereby expanding the internal cavity ofthe femur until a desired shape is created. According to aspects andembodiments of the present invention, to minimize trauma to a patientduring installation and operation of the improved broaches, the surgeonchanges the angle of insertion of the broach, utilizing the doubleoffset of the handle to align the elongated member of the broach withthe long axis of the femur when approaching the femur through ananterior incision at the patient's hip.

To improve the alignment of the broach during insertion into the femur,various alignment systems and methods may be utilized, including, butnot limited to, mechanical referencing, alignment, and positioningdevices. Computer-assisted or computer-aided surgery systems can also beadvantageously used in conjunction with the improved broaches of theembodiments of the present invention. For example, the broaches can beused witn the sensors that track the instruments with respect to thepatient's femur, and a computer functionality processing informationprovided by the sensors and providing recommendations to the surgeon.The improved broaches can further comprise fiducials for tracking theinstrument during computer-assisted surgery. Robotic navigation devicesand surgical systems can also be used to navigate and operate theimproved broaches.

The improved broaches and method of their use according to aspects andembodiments of the present invention possess a number of advantages overthe conventional systems and methods. Some of the conventional methodsand devices for femoral preparation are designed with the goal ofminimizing the amount of bone resected from the greater trochanter togain access to the intramedullary cavity of the femur. To this end, theconventional systems employ the femoral broaches that are rotated alongthe medial arc of the patient's femur when preparing the femoral cavity.A surgeon uses a series of the increasing size broaches until anappropriate femoral cavity is created. In such conventional systems, thebroach handle is offset medially with respect to the part of the broachinserted into the femur. In contrast to the conventional systems, thebroach systems according to aspects and embodiments of the presentinvention are advantageously adapted for use with the anterior approachby incorporating a second, vertical, offset of the handle with respectto the part of the broach inserted into the femur during its operation.

According to aspects and embodiments of the present invention,variations are envisioned on the improved devices and systems used forcreating a femoral cavity during hip arthroplasty. The improved broachesof the present invention can be of variable shape, thereby allowingchanging their configuration to suit a particular surgical application.The broaches of variable shape can incorporate, for example, flexibleshafts that permit altering their shape. The broaches of variable shapecan also be modular, thereby allowing the user to custom-assemble abroach for a particular application. Also envisioned are flexiblereamers for opening, or reaming, a femoral canal, and flexible millingsystems for rotating into the femur. All of the embodiments providedherein can be used separately or in any combination.

Osteotome

FIGS. 7-11 show an improved femoral osteotome (200). The improvedfemoral osteotome (200) comprises a handle (202) an elongated shaft(202A) extending downward from the knob approximately in thez-direction. At the bottom of the handle shaft (202A), a first offset(204) extends approximately in the y-direction. At the other end of thefirst offset (204), a second offset (205) extends approximately in thex-direction. At the other end of the second offset (205), a shapingmember (201) is elongated downward approximately in the z-direction andis adapted for insertion into the femoral bone.

The double offset of the handle member (202) with respect to the shapingmember (201) simplifies the approach to the femur, and permits insertingand operating the osteotome through a minimally invasive surgicalincision, reducing the need for the posterior capsule resection duringanterior approach to the femur. In a preferred embodiment, thisconfiguration allows the surgeon to advantageously utilize the anteriorapproach over more invasive lateral or posterior approaches. The doubleoffset of the handle (202) with respect to the shaping member (201)permits aligning the shaping member (201) with the long axis of thefemur, at the same time directing the handle up and out of the surgicalsite, rendering vertical approach to the femur unnecessary.

During surgery, the first offset (204) elevates the handle (202) out ofthe wound during and upon insertion of the osteotome. When the patientis in a supine position, upon insertion, the handle (202) of theosteotome is elevated in a generally vertical direction. The secondoffset (204) minimizes the trauma to the bone and to the soft tissues.When the patient is positioned in a supine position on a surgical table,the second offset (204) locates the handle (202) away from the long theshaping member (201) in the general medial/lateral direction

In a preferred embodiment, the osteotome is a box osteotome comprising ashaping member (301) shown in FIG. 11. The shaping member (301) of thebox osteotome is of approximately box shape and comprises an open distalend (302) with a distal cutting edge (303). During hip arthroplasty, thebox osteotome cuts a box shape of the femoral bone to open the patient'sfemoral canal. In a preferred embodiment, the cutting member (301) ofthe box osteotome is approximately 1 to 1½ inches long.

The osteotomes according to the embodiment shown in FIGS. 7-11 can beadvantageously inserted through a minimally invasive surgical incisionand are particularly convenient for the anterior access to the femur,which is advantageous over the lateral or posterior access requiring thesurgical dissection of muscle tissue. In a preferred embodiment, theincision for inserting the improved osteotome is between approximately 4cm to approximately 16 cm.

In one embodiment, the improved osteotomes are advantageously, but notnecessarily, utilized in conjunction with the improved broaches. Morespecifically, the osteotome is used to remove the trochanteric fossa.When preparing the femur for installation of the prosthetic hip femoralcomponent, the surgeon uses the osteotome to resect at least a part ofthe femoral greater trochanter in order to gain access to the centralportion of the femur. According to aspects and embodiments of thepresent invention, to minimize trauma to the patient during operation ofthe improved osteotome, the surgeon changes the angle of insertion ofthe osteotome, utilizing the double offset of the handle toappropriately direct the elongated cutting member of the osteotome inthe greater trochanter resection.

To improve the alignment of the osteotome during insertion into thefemur, various alignment systems and methods may be utilized. Suchsystems may include mechanical referencing, alignment, and positioningdevices. Computer-assisted or computer-aided surgery systems can also beadvantageously used in conjunction with the improved osteotomes of theembodiments of the present invention. For example, the osteotomes can beused with the sensors' tracking instruments with respect to thepatient's femur and a computer functionality that processes theinformation provided by the sensors and, in turn, provides navigationalrecommendations to the surgeon. The improved osteotomes can furthercomprise fiducials for tracking the instrument during computer-assistedsurgery. Robotic navigation devices and surgical systems can also beused to navigate and operate the improved osteotomes.

System and Method for Improved Positioning of a Patient

The aspects and embodiments of the present invention provide a methodand system for improving patient positioning during hip arthroplasty.The improved method allows the surgeon better access to the hip joint,particularly to the femur. The improved method also and permits quickand simple modification of the conventional surgical tables to improvepatient positioning during hip arthroplasty.

According to an embodiment of the present invention schematicallyillustrated in FIG. 12, for hip replacement surgery, the patient (401)is placed on a surgical table (402) fitted with a mattress of variableconfiguration (403), such as, but not limited to, an air mattress or aninflatable mattress. When improved access to the proximal femur (404) isdesired during the surgery, the configuration of the mattress (403) isaltered to elevate the patient's torso (405) with respect to thepatient's leg (406). To this end, the mattress of variable configuration(403) may be placed under the patient's torso (405) with the leg (406)positioned on the surgical table (402). Increasing the height of themattress (403) elevates the patient's torso (405) relative to thepatient's leg. The torso's (405) elevation directs the proximal end ofthe femur (404) towards the surgical incision (the general direction ofthe long femoral axis is also indicated (408)). In one aspect, thisprovides the surgeon enhanced access to the femur for preparation of theintramedullary canal for total hip arthroplasty, without resecting theposterior capsule.

Thus, by using the variable configuration mattress to elevate the torsoof the patient relative to the patient's leg, the leg of the patientbecomes positioned at an angle relative to the torso, thereby allowingeasier access to the proximal femur at the hip joint. The concept ofusing the variable configuration mattress for positioning of the patientand the patient's body parts during surgery is not limited to hiparthroplasty, but can be adapted to other surgical procedures.

In a preferred embodiment, using the variable configuration mattressduring hip arthroplasty allows repositioning of the patient's legthroughout surgery to gain better access to the femur for installationof the femoral component of the prosthetic hip. With the variableconfiguration mattress, any operating room table can be adapted for sucha procedure, thereby avoiding the necessity of fitting the surgicalsuite with a table with a dropping end, such as a Judet table. Using thevariable configuration mattress increases the versatility of a surgicalsuite without incurring the significant cost of purchasing an additionalsurgical table.

In a preferred embodiment, the variable configuration mattress accordingto aspects and embodiments of the present invention is an inflatablemattress. An inflatable mattress is manufactured according to methodsknown to those of ordinary skill in the art. The variable configurationmattress can be sectional, allowing the user to alter the configurationof the mattress' sections in any desired combination. In this variation,for example, the configuration of the section of the mattress fittedunder the patient's torso may be altered to elevate the torso, or theconfiguration of the section of the mattress fitted under the patient'sleg may be altered to lower the limb, or both. The variableconfiguration mattress can incorporate side sections to prevent thepatient from rolling off the mattress. When an inflatable mattress isused, it is inflated to increase the height of the mattress or one ormore of its sections, and deflated to decrease the height of themattress or one or more of its sections. The air mattress can bedisposable or reusable depending on the materials used and the methodsof construction. The variable configuration of the inflatable mattress,including but not limited to the change of height of the mattress or itssections, can be utilized for positioning together with other devices,such as, but not limited to, sand bags or rigid pads.

Variations on the devices, instruments, systems, and methods accordingto preferred embodiments of the present invention are envisioned andfall within the scope of the present invention. In general, it is to beunderstood that the structures and methods according to aspects andembodiments of the present invention can vary, and can be modified inaccordance with a particular application for which they are used.Incorporation of various useful features by the structures and methodsand their use in conjunction with various devices and systems isenvisioned and falls within the scope of the present invention. It isalso to be understood that advantageous and distinguishing featuresaccording to embodiments of the present invention can be present invarious combinations.

In one of its aspects, the present invention also provides methods ofmodifying a shape of a proximal femur, including removing femoral boneor other tissues, or modifying the shape of the femoral bone or othertissues, using the instruments, systems, and methods according toembodiments of the present invention. Specifically, the presentinvention provides a method of preparing a femur of a patient forinstallation of a stem of a femoral component of a prosthetic hip duringhip replacement surgery. Shaping the proximal femur using theinstruments such as the osteotomes and the broaches, comprises insertingthe instrument into the hip joint, positioning the instrument, shapingthe tissue with the instrument, and removing the instrument from the hipjoint.

According to other aspects, the instruments, devices and systems, suchas broaches and osteotomes, are used to conduct joint replacementsurgery, such as hip replacement surgery. Such processes can include anyor all of inserting the instrument into a hip joint, positioning theinstrument, shaping the tissue with the instrument, removing theinstrument from the site, inserting a femoral prosthetic component, andcompleting the surgery.

The particular embodiments of the invention have been described forclarity, but are not limiting of the present invention. Those of skillin the art can readily determine that additional embodiments andfeatures of the invention are within the scope of the appended claimsand equivalents thereto.

1. An instrument for shaping a medullary canal for installation of aprosthetic stem component, comprising: (a) an elongated instrumenthandle defining: a first axis extending in a direction of elongation ofthe elongated instrument handle; a first plane; and a second plane,wherein the first plane and the second plane are substantiallyperpendicular to one another and intersect along the first axis; whereinthe elongated instrument handle further defines a plurality of thirdplanes and a plurality of fourth planes, the plurality of third planesbeing substantially parallel to the first plane, the plurality of fourthplanes being substantially parallel to the second plane, and each of theplurality of third planes being substantially perpendicular to each ofthe plurality of fourth planes; and wherein each of the first plane,second plane, plurality of third planes, and plurality of fourth planesat least partially lie within the elongated instrument handle; and (b)an elongated shaping member configured to shape bone, the elongatedshaping member including a distal portion with a rotational axis and aconnection portion configured to connect the elongated shaping member toa connecting member of the instrument, the connection portion of theelongated shaping member having a longitudinal axis and defining: afifth plane extending substantially parallel to a plane that containsthe rotational axis of the distal portion of the elongated shapingmember and the longitudinal axis of the connection portion of theelongated shaping member; a sixth plane, wherein the fifth plane andsixth plane are substantially perpendicular to one another; wherein theelongated shaping member further defines a plurality of seventh planesand a plurality of eighth planes, the plurality of seventh planes beingsubstantially parallel to the fifth plane, the plurality of eighthplanes being substantially parallel to the sixth plane, and each of theplurality of seventh planes being substantially perpendicular to each ofthe plurality of eighth planes; wherein each of the fifth plane, sixthplane, plurality of seventh planes, and plurality of eighth planes atleast partially lie within the elongated shaping member; and whereineach of the first plane, plurality of third planes, fifth plane, andplurality of seventh planes are substantially parallel, wherein each ofthe second plane, plurality of fourth planes, sixth plane, and pluralityof eighth planes are substantially parallel, wherein none of the firstplane and plurality of third planes intersect any of the fifth plane andplurality of seventh planes, and wherein none of the second plane andplurality of fourth planes intersect any of the sixth plane andplurality of eighth planes, and wherein the connecting member extendsbetween the elongated instrument handle and the elongated shaping memberand at least temporarily connects the elongated instrument handle to theelongated shaping member.
 2. The instrument of claim 1, wherein theconnection portion has a round cross section.
 3. The instrument of claim1, wherein the connection portion does not have a round cross section.4. The instrument of claim 1, wherein the elongated shaping member is anosteotome for resecting at least a portion of a femoral trochanter. 5.The instrument of claim 1, wherein the elongated shaping member is afemoral broach for preparation of a central femoral cavity for receivingthe stem of the prosthetic stem component.
 6. The instrument of claim 1,wherein the elongated shaping member is releasably connected to theinstrument.
 7. An instrument for shaping a medullary canal, comprising:(a) a handle including: a plurality of transverse cross sections; afirst centroid located on a first cross section of the handle; a secondcentroid located on a second cross section of the handle; the firstcentroid and second centroid defining a handle axis; (b) a shapingmember including structure configured to shape bone, the shaping memberalso including: a plurality of transverse cross sections; a thirdcentroid located on a first cross section of the shaping member; afourth centroid located on a second cross section of the shaping member;the third centroid and the fourth centroid forming a shaping memberaxis; and (c) a connecting member connecting the handle and the shapingmember, the connecting member having a plurality of transverse crosssections; wherein the handle axis and the shaping member axis define areference plane and wherein at least one centroid located on aconnecting member cross section is not contained in the reference plane.8. The instrument of claim 7, wherein the shaping member is an osteotomefor resecting at least a portion of a femoral trochanter.
 9. Theinstrument of claim 7, wherein the shaping member is a femoral broachfor preparation of a central femoral cavity for receiving a stem of afemoral component of a prosthetic hip.
 10. The instrument of claim 7,wherein the shaping member is releasably connected to the instrument.11. An instrument for shaping a medullary canal, comprising: (a) ahandle that includes a handle longitudinal axis; (b) a shaping memberincluding structure configured to shape bone, the shaping memberincluding a shaping member longitudinal axis; and (c) a connectingmember that connects the handle to the shaping member; wherein thehandle longitudinal axis and the shaping member longitudinal axis areparallel; wherein the handle longitudinal axis and the shaping memberlongitudinal axis define a reference plane; and wherein at least onecentroid located on a connecting member cross section is not containedin the reference plane.
 12. The instrument of claim 11, wherein theshaping member is an osteotome for resecting at least a portion of afemoral trochanter.
 13. The instrument of claim 11, wherein the shapingmember is a femoral broach for preparation of a central femoral cavityfor receiving a stem of a femoral component of a prosthetic hip.
 14. Theinstrument of claim 11, wherein the shaping member is releasablyconnected to the instrument.
 15. An instrument for shaping a medullarycanal, comprising: (a) a handle that includes a handle longitudinalaxis; (b) a shaping member including structure configured to shape bone,the shaping member including a shaping member longitudinal axis; and (c)a connecting member that physically connects the handle to the shapingmember; wherein the handle longitudinal axis and the shaping memberlongitudinal axis are parallel; and wherein, in a plane orthogonal tothe handle longitudinal axis and to the shaping member longitudinalaxis, the connecting member is S shaped or Z shaped.
 16. The instrumentof claim 15, wherein the shaping member is an osteotome for resecting atleast a portion of a femoral trochanter.
 17. The instrument of claim 15,wherein the shaping member is a femoral broach for preparation of acentral femoral cavity for receiving a stem of a femoral component of aprosthetic hip.
 18. The instrument of claim 15, wherein the shapingmember is releasably connected to the instrument.
 19. An instrument forshaping a medullary canal, comprising: (a) a handle that includes ahandle longitudinal axis; (b) a shaping member including structureconfigured to shape bone, the shaping member including a shaping memberlongitudinal axis; and (c) a connecting member that physically connectsthe handle to the shaping member; wherein the handle longitudinal axisand the shaping member longitudinal axis are parallel; and wherein, in aplane orthogonal to the handle longitudinal axis and to the shapingmember longitudinal axis, the connecting member extends in more than onedirection.
 20. The instrument of claim 19, wherein the shaping member isan osteotome for resecting at least a portion of a femoral trochanter.21. The instrument of claim 19, wherein the shaping member is a femoralbroach for preparation of a central femoral cavity for receiving a stemof a femoral component of a prosthetic hip.
 22. The instrument of claim19, wherein the shaping member is releasably connected to theinstrument.
 23. An instrument for shaping a medullary canal comprising:(a) a handle that includes a handle longitudinal axis; (b) a shapingmember including structure configured to shape bone, the shaping memberincluding a shaping member longitudinal axis; and (c) a connectingmember that physically connects the handle to the shaping member;wherein the handle longitudinal axis and the shaping member longitudinalaxis are parallel; and wherein, in a plane orthogonal to the handlelongitudinal axis and to the shaping member longitudinal axis, theconnecting member extends in a first direction and in a second directionthat is not parallel to the first direction.
 24. The instrument of claim23, wherein the shaping member is an osteotome for resecting at least aportion of a femoral trochanter.
 25. The instrument of claim 23, whereinthe shaping member is a femoral broach for preparation of a centralfemoral cavity for receiving a stem of a femoral component of aprosthetic hip.
 26. The instrument of claim 23, wherein the shapingmember is releasably connected to the instrument.
 27. An instrument forshaping a medullary canal, comprising: (a) a handle that includes ahandle longitudinal axis and an end; (b) a shaping member includingstructure configured to shape bone, the shaping member including ashaping member longitudinal axis and a tip; and (c) a connecting memberthat physically connects the handle to the shaping member; wherein thehandle longitudinal axis and the shaping member longitudinal axis areparallel; and wherein the instrument is configured to rotate about twoaxes that are orthogonal to the handle longitudinal axis and to eachother, when the tip of the shaping member is constrained and a force isapplied to the end of the handle coaxial to the handle longitudinalaxis.
 28. The instrument of claim 27, wherein the shaping member is anosteotome for resecting at least a portion of a femoral trochanter. 29.The instrument of claim 27, wherein the shaping member is a femoralbroach for preparation of a central femoral cavity for receiving a stemof a femoral component of a prosthetic hip.
 30. The instrument of claim27, wherein the shaping member is releasably connected to theinstrument.